The invention relates to a matrix type magnetic head for recording/reading that is applicable especially to the recording/reading of multiple-track magnetic tapes.
The French patent applications 2 630 853 and 2 648 608 describe matrix type magnetic heads for recording and reading that can be used to carry out high-density recording/reading operations on a recording medium. For example, such magnetic heads are capable of recording on up to 1,024 tracks in parallel on an 8 mm wide magnetic tape.
These matrix heads can be made by hybrid technologies combining steps of sawing, winding, bonding, and thin-layer deposition. Methods of manufacture are described for example in the French patent 2 648 940. Furthermore, these matrix heads may be obtained entirely by the deposition of thin layers, using technologies known as "integrated" technologies. With integrated technologies, the conductors are no longer wound wires but etched conductor films. A number of patents describe this technology.
A major constraint of integrated technologies is that the cost of manufacture of the heads is nearly proportional to their surface area. A major goal therefore is to reduce the surface area of the heads.
When a thin-layer matrix type reading head is made, two alternatives emerge for the connection of this head to its electronic circuitry:
Front-face connection system: wires are soldered directly to the thin-layer conductors. The excess thicknesses by this soldering precludes efficient contact between the tape and the head in the vicinity of the soldered wires. It then becomes necessary to take these solders to the exterior of the tape (on either side). The total height of the head is therefore dictated by this constraint. In certain configurations, this amounts to the considerable over-sizing of the real head. PA1 Rear-face connection: to avoid the drawbacks of the front-face connection system, it is possible to connect the writing head to the rear face by making conductive passages (for example, via holes) in the substrate. PA1 an electrically non-conductive ceramic substrate having a first main face and a second main face, each provided with connection areas, the two areas of the two faces being interconnected in sets of two by internal connection elements; PA1 a layer with high magnetic permeability deposited on the first face of the substrate and bearing a first series of row conductors and a second series of column conductors intersecting the row conductors, each conductor being connected to a connection area of the first face; PA1 pairs of magnetic poles located substantially at the intersection of a row conductor and a column conductor, the poles of a pair being separated by a gap space and being magnetically coupled to the layer with high magnetic permeability in two opposite zones defined by the intersection of a row conductor and a column conductor.
At present, the formation of holes in silicon substrates on an industrial scale has not been mastered.
The invention provides a solution to this problem.